Image Analysis and Untargeted Metabolomics Reveal Potential Phytotoxins from Fusarium venenatum Against Major Parasitic Weed Phelipanche ramosa (L.) Pomel

Branched broomrape (<i>Phelipanche ramosa</i> (L.) Pomel), an obligate parasitic weed with a wide host range, is known for its devasting effects on many crops worldwide. Soil fungi, notably <i>Fusarium</i> sp., are described as pathogenic to broomrape, while the hypothesis of the phytotoxicity of fusaric acid produced by <i>F. verticillioides</i> for parasitic weeds of the genus <i>Orobanche</i> has been proposed. Using image analysis and untargeted metabolomics, this study investigated fungal metabolites phytotoxic for <i>P. ramosa</i> and produced by the <i>F. venenatum</i> MIAE02836 strain, isolated from symptomatic broomrapes and identified as a promising candidate for broomrape biocontrol. Phytotoxicity tests of crude extracts from the fungus alone or in interaction with broomrape on <i>P. ramosa</i> microcalli and quantification of necrosis by image analysis confirmed the phytotoxic potential of <i>F. venenatum</i> MIAE02836 metabolites towards the early developmental stages of <i>P. ramosa</i>. Data analysis of a non-targeted metabolomics approach revealed numerous metabolites produced by <i>F. venenatum</i> MIAE02836. Four of them, accumulated during interaction with the parasitic plant, are known for their phytotoxic potential: maculosin, cyclo(Leu-Phe), phenylalanyl-D-histidine and anguidine. These results suggest that combining image acquisition of the microcalli screening test and untargeted metabolomic approach is an interesting and relevant method to characterize phytotoxic fungal metabolites.